Researchers at the Harvard School of Public Health examined the association between eating whole grains and the risk of death using data from two studies that included more than 118,000 health professionals (women and men) for more than 20 years. All the participants were free of cancer and cardiovascular disease when the studies began. Participants filled out surveys every two to four years about several lifestyle habits, including whole grain consumption.

During the long study period, the researchers documented 26,920 deaths. Compared with those who ate the least amount of whole grains, about one-third fewer of those who ate the most whole grains died during the study period.

The researchers estimated that every 28-gram serving (just less than 1 ounce) of whole grains per day was associated with a 5 percent lower risk of death from any cause during the study, and a 9 percent lower risk of dying from cardiovascular disease. The researchers found no association between eating whole grains and lower risk of dying from cancer.

Although those who ate the most whole grains also had, on average, healthier habits than other study participants, the researchers accounted for potential confounding factors such as smoking and body mass index in their analysis. The link between whole grain consumption and lower risk of early death remained once these statistical adjustments were made.

“These findings further support current dietary guidelines that recommend increasing whole grain consumption to facilitate primary and secondary prevention of chronic disease and also provide promising evidence that suggests a diet enriched with whole grains may confer benefits toward extended life expectancy,” the researchers concluded.

In the field, grains comprise three parts: the bran, an outer shell: the germ, the inside of the seed that can be used to grow a new plant; and the endosperm, which can be used as a food supply by the germ. Many manufacturing processes strip the bran and germ and create food only from the endosperm. For a food to to be sold as a whole grain, the endosperm, germ, and bran must be present in the same proportion as when grown.

"As long as the right proportion is there, technically, whole grains can be rolled, ground, cooked, parboiled, extruded, pearled, and even milled," according to Runner's World Fuel School columnist Pamela Nisevich Bede, M.S., R.D.[3] "You can be sure your bread or pasta or side dish is whole grain if the ingredient list includes the word 'whole' as the first ingredient rather than seemingly healthy but not necessarily whole-grain terms like 'unbleached' or 'stone ground.'"